The proposed program is directed toward continuing the overall objective of the past: prevention of chronic diseases, with particular emphasis on chronic diseases of infectious origin. The work is conducted in the Boston City Hospital and its surrounding community, so there is special concern with chronic diseases in a low income urban population. The areas for special study include prevention of prematurity and perinatal morbidity, with emphasis on the role of genital mycoplasmas (T strains and M. hominis), and of bacteriuria of pregnancy. Large scale ecological study in community populations, as well as studies in the prenatal clinic, give promise of yielding useful information on the distribution of these infectious agents, the detection of tissue invation by suitable antibody techniques, (including measurement of IgG, IgM, and IgA), and the delineation by controlled trials of etiological relationships. Interactive variables will be weighed, using multiple regressive techniques, against those factors that have been defined, by epidemiological and clinical analysis to relate quantitatively to prematurity and perinatal mortality. Additionally, long term studies will be conducted of the role of bacteriuria in relation to renal disease and as a predictor of excess mortality. Several approaches to treatment aimed at improving present methods of treatment will be assessed in controlled trials. Further epidemiological studies will be conducted of the role of bacteriuria in the genesis of hypertension. A few hypothesis will also be tested for which supporting evidence has been obtained, namely that essential hypertension is an acquired disease of early childhood. A search will be begun for etiological factors in hypertension that operate during early childhood. Additionally, observations on the role of infectious agents in other disease states, and the use of microbial models in elucidating mechanisms of disease (such as in erythropoietic protoporphyria) will be continued.